This invention relates generally to a pressure responsive fluid shut-off device and, more particularly, to a device for shutting off a supply of liquid propane (LP) gas in the event that a malfunction in a supply system results in excessive gas pressures.
The appearance of excessive gas pressures in LP gas supply systems introduces substantial risk of fire and explosion. In most domestic LP gas systems, fire and explosion hazards are prevented by a regulator located between an LP gas supply tank and a supply line feeding appliances encompassed by the system. The regulator functions to reduce supply tank pressure, typically above 100 psi, to a safe line pressure of less than 1 psi. However, malfunctions in such regulators often lead to the appearance of hazardous gas pressures in supply lines. A common cause of regulator malfunction is a blockage of vent openings that establish atmospheric reference pressures in typical differential pressure responsive regulators. Upon loss of an accurate atmospheric pressure reference, a regulator can cease to function properly and in some instances, allow a hazardous increase in gas pressure. The use of an atmospheric pressure reference in conventional LP gas regulators leads also in certain instances to the occurrence of dangerous gas leakage. Such leaks can result from an internal seal failure that permits gas leakage into an atmospheric reference chamber and out of an atmospheric vent opening into the immediate environment.
The object of this invention, therefore, is to provide a pressure responsive shut-off device that will eliminate the problems inherently present in LP gas regulators that utilize atmospheric reference pressures.